In the production of imitation meat protein materials, various methods have been known. For example, it has been known that an imitation meat protein material can be produced by spinning, injection, discharge or extrusion of a proteinaceous raw material and, usually, to preserve it, the resulting material is dried. Imitation meat protein materials thus obtained have various structures such as fibrous structures, network structures, rope-like structures, membrane-like structures and the like. Among them, in order to produce an imitation meat protein material by extrusion, a single screw extruder has been predominantly used to cook and extrude a raw material and, usually, the resulting material has a swollen network structure.
However, recently, a twin-screw extruder has been introduced as one of advanced techniques and studied. And, it has been known that, in comparison with a conventional single screw extruder, a twin-screw extruder has various advantages such as constant extrusion, less scorching, broad selectivity of raw materials and the like. Further, it has been known that the material obtained has a good fibrous structures, and texture and mouthfeel thereof very much resemble to meat.
On the other hand, since these conventional known imitation meat protein materials are not flavored, usually, they are secondarily processed by flavoring according to particular purposes and preference. In this respect, although flavoring can be effected freely to meet a particular product, there is such defect that flavor and taste thus provided by the secondary processing are liable to be lost by chewing and to leave only an aftertaste derived from the raw material thereof.
In addition, although a fried product is often produced from a dried imitation meat protein material by reconstituting the material with water or hot water and flavoring the material during reconstitution and then frying the resulting flavored material, the flavor and taste of the flavored material is also liable to be lost by chewing.
Thus, it has not been known heretofore in the prior art that an imitation protein material may be primarily or originally flavored during cooking with a twin-screw extruder to provide good meat-like flavor and taste which are hardly lost by chewing.